JPH08157560A - Semiconductor-sealing epoxy resin composition - Google Patents

Abstract

PURPOSE: To provide a semiconductor-sealing epoxy resin compsn. which has a low viscosity in a melt state, can be increased in the inorg. filler content thereof, and can form a semiconductor device low in thermal stress and high in strength when heated and hence excellent in cracking resistance, by blending a specific bifunctional epoxy resin with an epoxy resin other than the above- mentioned epoxy resin, a specific phenolic curing agent and an inorg. filler at a specific proportion. CONSTITUTION: This epoxy resin compsn. comprises as the indispensable components (A) at least 90%. bifunctional epoxy resin of the formula obtd. by molecular distillation, (B) an epoxy resin other than the component (A), (C) a phenolic curing agent comprising as the main component a resin contg. at least 3 phenolic hydroxyl groups in the skeleton thereof, and (D) an inorg. filler, provided that the proportion of the component (A) to the total epoxy resins (A+B) is at least 90wt.%. and the proportion of the component (D) to the whole resin compsn. is 85 to 97wt.%. The epoxy resin as the component (A) is obtd. by molecular distillation of a crude epoxy resin in a degree of vacuum of 1 to 100×10<-3> Torr at 180 to 260 deg.C. The kind of inorg. filler is not particularly limited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation.

[0002]

2. Description of the Related Art In recent years, as semiconductor elements have become larger and more highly integrated, when semiconductors are encapsulated with conventional epoxy resin compositions, the difference in linear expansion coefficient between the chip or lead frame and the encapsulating resin. There has been a problem that the reliability of the semiconductor component is deteriorated, such as cracks in the chip caused by the thermal stress generated by the chip and the cutting of the bonding line. In addition, with the increasing integration of semiconductors, methods such as immersing resin-sealed semiconductors in molten solder or mounting them with infrared reflow equipment have been adopted. There was a problem of causing cracks.

It is effective to reduce the thermal stress and increase the content of an inorganic filler such as silica filler in order to prevent package cracks generated during mounting, to reduce the linear expansion coefficient and to enhance the package strength during heating. Is known to be. In particular, in the case of a package crack, a crack occurs when the moisture generated by the moisture absorption of the package itself is abruptly vaporized in the package by the heat treatment during mounting and the stress generated exceeds the strength of the package itself. Therefore, increasing the content of the inorganic filler not only enhances the strength of the package under heat, but also reduces the absolute amount of moisture absorbed by the resin part, which helps prevent package cracks during mounting (tail shape). Masatsugu et al., “Low thermal expansion epoxy resin-based molding material” The 38th Thermosetting Resin Lecture Meeting, 123-126 (1988), Toshiaki Ishii et al., “Particle size of spherical filler on fluidity of epoxy molding material” Influence of distribution "Fourth
3rd Thermosetting Resin Lecture Meeting, 141-144 (1993)).

Epoxy resins widely used for semiconductor encapsulation have been synthesized by reacting a bisphenol compound with epichlorohydrin. The epoxy resin (1) produced at the initial stage of the reaction and the unreacted bisphenol compound (2 )

[0005]

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[0006]

Embedded image React with each other to produce an epoxy resin (3) containing a high molecular weight substance.

[0007]

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Alternatively, a high molecular weight compound represented by the general formula is obtained by reacting with the epoxy resin (1) in which the hydroxyl group of the secondary alcohol formed during the reaction of the epoxy resin (1) with the unreacted bisphenol compound (2) is formed or epichlorohydrin. An epoxy resin (4) containing is produced.

[0009]

[Chemical 4]

Since such an epoxy resin has poor crystallinity, it is difficult to handle at the time of molding, and since it contains a high molecular weight substance, the viscosity of the epoxy resin is high, and when the content of silica filler is increased, the fluidity at the time of molding becomes high. In order to obtain a good package molded product, the filler content must be suppressed to less than 85% by weight, and the package crack resistance during mounting was also insufficient.

[0011]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve the above problems,
An object of the invention is to provide a resin composition for encapsulation that provides a highly reliable semiconductor device having high resistance to thermal history during mounting without impairing moldability.

[0012]

The present invention provides an epoxy resin containing (A) 90% or more of a difunctional epoxy resin represented by the general formula (1) obtained by molecular distillation.

[0013]

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(B) Epoxy resin other than component (A),
(C) Phenolic curing agent containing as a main component a resin containing at least three phenolic hydroxyl groups in the skeleton, and (D) an inorganic filler are essential components, and the total epoxy resin (A) + (B) is 90% by weight of component (A)
The above is the epoxy resin composition for semiconductor encapsulation, which contains the inorganic filler (D) in a proportion of 85 to 97% by weight with respect to the entire resin composition.

The epoxy resin represented by the general formula (1) is synthesized by reacting a bisphenol compound represented by the following general formula (2) with epichlorohydrin.

[0016]

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This reaction can be carried out by the same operation as the reaction for synthesizing a usual bisphenol A type epoxy resin. For example, a bisphenol compound represented by the general formula (2) is dissolved in epichlorohydrin in a molar ratio of about 10 times, and then dissolved in the presence of sodium hydroxide in an amount of 30 to 100.
C., preferably 50 to 80.degree. C. for 1 to 5 hours. The amount of sodium hydroxide used at this time is preferably approximately equimolar to 1 mol of the bisphenol compound. During the reaction, excess epichlorohydrin is distilled off under reduced pressure, and after the reaction, a solvent such as methyl isobutyl ketone is added and dissolved, and the inorganic salt formed is filtered and washed with water to be removed. After that, the solvent is distilled off again under reduced pressure. The epoxy resin obtained here is an epoxy resin containing a high molecular weight substance and by-products. Therefore, this epoxy resin is further added to 180 to 260.
The target epoxy resin can be obtained by molecular distillation at a temperature of ℃ and a degree of vacuum of 1 to 100 × 10 ^-3 Torr. Here, 90% or more of the bifunctional epoxy resin represented by the general formula (1) means the general formula (1) obtained by GPC.
3 shows the ratio of the peak area to the whole.

The epoxy resin used in the present invention preferably contains 90% or more of the epoxy resin represented by the general formula (1). This is because the epoxy resin represented by the general formula (1) has a low viscosity, and when a phenolic curing agent and an inorganic filler are blended to form a molding material, the melt viscosity at the time of molding can be lowered, and as a result, It is preferable because the filling rate of the inorganic filler can be increased. If the epoxy resin of the general formula (1) is less than 90% in the epoxy resin component, the effect of lowering the viscosity and increasing the filling cannot be obtained, which is not preferable.

In the epoxy resin component, the ratio of the component (B) to the total amount of epoxy resin (A) + (B) is 10% by weight.
Epoxy resins other than the general formula (1) can be used within the range of less than. Examples of these are novolac-based epoxy resins obtained by epoxidizing a novolac compound which is a reaction product of phenols such as phenol and o-cresol with formaldehyde, tris- (4-hydroxyphenyl) -methane, 1,1,2,2. -Glycidyl ether compounds derived from trihydric or higher phenols such as tetrakis (4-hydroxyphenyl) ethane, bisphenol A,
Glycidyl ether compounds derived from dihydric phenols such as bisphenol F, hydroquinone and resorcin, or halogenated bisphenols such as tetrabromobisphenol A, and polyhydric phenols obtained by the condensation reaction of phenols and aromatic carbonyl compounds Glycidyl ether compound, p-aminophenol, m-aminophenol, 4-aminometacresol, 6-aminometacresol, 4,4'-diaminodiphenylmethane, 3,
3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,4-bis (4-aminophenoxy) benzene, 1,4
-Bis (3-aminophenoxy) benzene, 2,2-bis (4-
Aminophenoxyphenyl) propane, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine, p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanebis (methyl) Amine), amine-based epoxy resin derived from 1,3-cyclohexanebis (methylamine), etc., derived from aromatic carboxylic acid such as p-oxybenzoic acid, m-oxybenzoic acid, terephthalic acid and isophthalic acid Glycidyl ester compounds, hydantoin epoxy compounds derived from 5,5-dimethylhydantoin, etc., 2,2-
Bis (3,4-epoxycyclohexyl) propane, 2,2-
Alicyclic epoxy resins such as bis [4- (2,3-epoxypropyl) cyclohexyl] propane, vinylcyclohexenedioxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, N,
N-diglycidylaniline and the like are used, and one or more of these epoxy resins are used.

The curing agent used in the epoxy resin composition of the present invention preferably contains a resin containing at least three phenolic hydroxyl groups in its skeleton as a main component.
When the number of phenolic hydroxyl groups is 2 or less, the bifunctional epoxy resin represented by the general formula (1) cannot be sufficiently crosslinked and cured, and as a result, heat resistance and physical properties are deteriorated, which is not preferable.

The structure of the phenol-based curing agent is not particularly limited, but an example is Tris- (4-
(Hydroxyphenyl) ethane, phenol novolac,
Tri- or higher valent phenols represented by o-cresol novolac, naphthol novolac, polyvinylphenol, etc., and further phenols, naphthols or bisphenol A, bisphenol F, bisphenol S,
4,4'-biphenol, hydroquinone, resorcin,
It is a polyhydric phenolic compound synthesized by a condensing agent such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, p-xylylene glycol of dihydric phenols such as naphthalenediol.

The inorganic filler used in the present invention is preferably contained in a proportion of 85 to 97% by weight based on the total resin composition. If the amount is 85% by weight or more, the water absorption of the semiconductor itself obtained by curing from the epoxy resin composition decreases, and the strength of the package at the time of heating improves, so cracks occur in the package due to thermal history during solder connection mounting. It is possible to prevent this. On the other hand, when it exceeds 97% by weight, the melt viscosity at the time of molding becomes high,
This is not preferable because the fluidity is extremely lowered and a good molded product of the resin-encapsulated semiconductor cannot be obtained.

The inorganic filler of the present invention is not particularly limited, but silica powder such as spherical or crushed fused silica and crystalline silica, alumina powder, glass powder and the like can be used. It goes without saying that it is possible to use two or more fillers in combination.

The epoxy resin composition for semiconductor encapsulation of the present invention contains a curing accelerator, a flame retardant, a filler, a colorant, a release agent and a surface treatment agent.

Examples of the curing accelerator include imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, amines such as 2,4,6-tris (dimethylaminomethyl) phenol and benzyldimethylamine, and the like. Tributylphosphine, triphenylphosphine,
Organophosphorus compounds such as tris (dimethoxyphenyl) phosphine, triphenylphosphine-triphenylboron, tetraphenylphosphine-tetraphenylborate and the like can be mentioned. It is possible to use two or more kinds in combination.

As the flame retardant, any known addition type or reaction type can be used. For example, brominated epoxy resin derived from tetrabromobisphenol A, red phosphorus, phosphoric ester, etc. can be used. Examples include phosphorus-based flame retardants, nitrogen-based flame retardants such as melamine, guanidine, and melamine cyanurate, and inorganic flame retardants such as aluminum hydroxide, magnesium hydroxide, antimony trioxide, and antimony pentoxide. If necessary, two or more kinds may be used in combination.

As the colorant, pigments, dyes and the like can be used, but it is usually preferable to use carbon black or the like.

Examples of the releasing agent include natural wax, synthetic wax, higher fatty acid or metal salt thereof, paraffin and the like, but are not particularly limited thereto.

The surface treatment agent used in the present invention is a surface treatment agent for a filler, and a known silane coupling agent, titanate type or aluminum type coupling agent or the like can be used.

The epoxy resin composition for semiconductor encapsulation of the present invention is excellent in fluidity at the time of molding even if the content of the inorganic filler is increased to 85% or more by having the constitution as described above. It is possible to obtain a good resin-sealed semiconductor. Furthermore, the package of this semiconductor device has a smaller amount of hygroscopicity than the conventional package due to the high content of the filler, and has a high strength at the time of heat, so that even if it is subjected to a high temperature heat history applied during mounting on a printed circuit board, etc. It is possible to provide a highly reliable semiconductor device without causing a package crack.

[0031]

EXAMPLES The present invention will now be described in more detail with reference to examples.

(Example 1)

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Epoxy resin (B-1) (epoxy equivalent: 17) obtained by glycidyl etherification of
1 [g / eq]) (containing the bifunctional epoxy resin represented by the above (1) at 98% / calculated from the ratio of the peak area of the above (1) measured by GPC to the whole), Nippon Kayaku Co., Ltd. Brominated novolac type epoxy resin BREN-SL (epoxy equivalent: 275 [g / eq]), Sumitomo Dures Co., Ltd. phenol novolac resin PR-51714 (hydroxyl equivalent: 1
03 [g / eq]), spherical fused silica powder with an average particle size of 11 μm, spherical fused silica powder with an average particle size of 30 μm, crushed fused silica powder with an average particle size of 6 μm, hardening accelerator (triphenylphosphine), and other additions The agents were mixed in the ratios shown in Table 1, kneaded at 110 ° C. for 6 minutes using a mixing roll, and then cooled and pulverized to prepare a resin composition for semiconductor encapsulation. This encapsulating resin composition was transfer-molded under the condition of 175 ° C./3 minutes and post-cured at 175 ° C. for 6 hours to prepare a molded test piece.

The bending strength (JI
SK6911) was measured at 240 ° C. Also, TM
The linear expansion coefficient and the glass transition temperature were measured by A (thermo-mechanical test). Further, after molding 80pinQFPIC and post-curing, moisture absorption treatment was performed for 24 hours, 72 hours, and 168 hours in a constant temperature and humidity machine at 85 ° C and 85%, and then treated with an IR reflow device (240 ° C / 10 seconds), and packaged. The crack was observed. Table 2 shows the results.

(Examples 2 to 3 and Comparative Examples 1 to 6) After mixing the materials in the proportions shown in Table 1, various physical properties were measured in the same manner as in Example 1. The measurement results are shown in Table 2.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

The epoxy resin composition for semiconductor encapsulation obtained according to the present invention has a low viscosity in a molten state.
It is possible to increase the content of the inorganic filler, and the obtained semiconductor device has a small thermal stress and a high strength at the time of heating, and therefore has excellent crack resistance.

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Claims (3)

[Claims] 1. An epoxy resin comprising (A) 90% or more of a difunctional epoxy resin represented by the general formula (1), which is obtained by molecular distillation. (B) An epoxy resin other than the component (A), (C) a phenolic curing agent containing as a main component a resin containing at least three phenolic hydroxyl groups in the skeleton, and (D) an inorganic filler as essential components. The ratio of the component (A) to the total epoxy resin (A) + (B) is 90% by weight or more, and the (D) inorganic filler is 85 to 97% by weight with respect to the entire resin composition. An epoxy resin composition for semiconductor encapsulation, characterized in that it is contained in a ratio. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the resin containing at least three phenolic hydroxyl groups in the skeleton is 50% by weight or more among the phenolic curing agent components. 3. A curing accelerator, a flame retardant, a filler, a colorant,
The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, further comprising a release agent and a surface treatment agent.